What speaker cable made a major difference in the sound quality of your speakers??

Don't waste your money...check out http://www.laventure.net/tourist/cables.htm
they have a very good article on speaker wires and connections.  Thoughts and opinions on the matter. 

I use .9999 "pure" silver made my own speaker wires, and interconnects once again all silver.  They have blown away every name brand and that is no b.s. 

I understand that some or most can not make their own, the above mentioned website also sells them complete.  Still cheaper than highly over priced name brands.  

It is worth a read....that is free...the result could be priceless.

rrwolfgram,

My silver wires also blew away every brand name I have ever had. Thanks very much for this link.

Transparent.

I put together some .999 silver loudspeaker cables a few months ago using info from the website @rrwolfgram mentioned and couldn't be happier with the results. Total cost for an 8' pair was just shy of $200. 

Audio Note SPx silver Litz, one of the few components I doubt I will ever replace.  The retail price is very expensive but I managed to buy mine as a demo from an Audio Note dealer within your budget.